In the prior art, when extruding plastic pipe with an extrusion die having inner and outer die portions, the inner die portion is typically secured to a central or inner hub of a spider pipe. The central hub is supported within the spider pipe by straight spider webs or legs. Polymer flowing through the spider pipe towards the dies must flow around the spider legs, separating at the upstream side of the spider legs and then rejoining together at the downstream side. In some situations, the polymer rejoins together in an incomplete manner, resulting in weld or spider lines on the inside of the pipe when extruded, and making the wall thickness of the pipe uneven. The wall thickness of the pipe is thinner along the weld or spider lines, and thicker in the regions between the spider lines.